Low pressure torch



April 29, 1969 J. N. JOHNSON 3,441,360

LOW PRESSURE TORCH Filed Nov. 22, 1966 INVENTOR. J05PH M JOHA/50N ATTORNEY United States Patent US. Cl. 431-345 7 Claims ABSTRACT OF THE DISCLOSURE A self-regulating, low pressure torch which mixes a large volume of air with the incoming combustion gas. The torch comprises a gas inlet nozzle mounted within an enlarged tubular handle member, a combustion chamber located forward of said inlet nozzle, and an air passage means in said tubular member whereby air flows through said tubular member and around said gas inlet nozzle to mix with the gas in the combustion chamber, while providing air cooling means for the handle member.

This invention is concerned with a low pressure gas torch, and is more particularly directed to the nozzle portion of such a torch.

In low pressure torches previously known the incoming gas under pressure was mixed with air that was heated and of a relatively low volume. As a result incomplete combustion occurred. Also such known devices exhibit the characteristic of having the flame extinguished by the backfiow of hot gases when the flame is brought too near the work or when the incoming gas flow is increased. Such known devices further give out odor due to the unburned gases flowing therefrom.

It is therefore one object of the invention to provide a low pressure torch which mixes a large volume of air with the incoming combustion gas. It is a further object of the invention to provide a low pressure torch in which the amount of air which is mixed with the gas is self-regulating, i.e the volume of air increases automatically as the volume of incoming combustion gas is increased. A still further object of the invention is to provide a multipurpose low pressure gas torch which furnishes various size flames Without the necessity of changing nozzles. Still another object of the invention is to provide a low pressure gas torch constructed from standard or stock parts without the necessity of providing special castings or housings. These and further objects of the invention will become more readily apparent from a reading of the description following hereinafter and from an examination of the drawings, in which:

FIGURE 1 is an exploded perspective view of a preferred embodiment of the low pressure torch of the invention;

FIGURE 2 is a cross-sectional view through the low pressure torch of FIGURE 1, shown in assembled position;

FIGURE 3 is a side view, partially in cross-section, of a modified torch of the invention; and

FIGURE 4 is a cross-sectional view taken along line 4-4 of FIGURE 3.

The low pressure torch of the invention comprises a tubular handle within which the gas supply is led. Within the tubular handle is suspended a nozzle to which the line is connected and from which the gas emits. The emitting jet of gas flows through a relatively long tube to a larger tube where combustion takes place.

Referring now to FIGURE 1, wherein a preferred embodiment is shown, it is seen that the torch 1 comprises a series of tubes interconnected in such a manner as to provide the indicated nozzle structure. A front tubular 3,441,360 Patented Apr. 29, 1969 "ice member 2 is affixed as by a press fit, welding or fastening to a bushing 6 which is in turn pressed or clamped onto a longer and smaller diameter tube 4, Formed within tube 2 is the combustion chamber 8 which also serves as a second mixing chamber, as explained hereinafter.

The other end of the tube 4 is fitted into a housing member 10 which has its outer surfaces 12 and 14 knurled, and has a recess 16 into which the tube 4 is affixed. The member 10 has a reduced section 17 upon which the handle 72 is slidably mounted. A still further reduced diameter housing extension 18 is provided to receive the gas nozzle 26. The extension 18 is provided with a pair of openings 20 and 22 which provide ingress of air to the first mixing chamber or interconnecting tube 4. An internally threaded insert member 24 is pressed into or preferably affixed to the inside of the reduced diameter housing section 18.

The gas nozzle 26 has a first outer threaded section 28 which is threaded into the insert 24 and spaced therefrom by means of the lock washer 36 and flat washer 38. A second outer threaded section 30 is also provided on the nozzle 26. Internally of the nozzle there is provided an internally threaded passage 46 which terminates in a valve seat 34 and communicates with a jet passage 32 of any predetermined dimension.

A valve member 42 is provided to cooperate with the gas nozzle in order to control the fiow of gas therethrough. The valve member 42 comprises the valve stem 56 which has the internal passage 54'extending completely therethrough and terminates in an oifset passage 56. The valve 42 is externally threaded at 52 so as to be movably positionable within the threaded passage 40 of the gas nozzle 26. The forward portion of the valve member is provided with a solid tip 58 to serve as the valve which cooperates with the valve seat 34 to close olf or control the degree of communication of the offset passage 56 with the jet passage 32.

A valve cap 44 having the internal threads 46 serves as the means for fastening the valve member 42 to the gas nozzle 26. A packing 48 is interposed between the cap 44 and the threaded section 30 of the gas nozzle to prevent leakage of gas therefrom.

The rear end of the valve member 42 is provided with opposed mounting bosses 60 and 62 which may be internally (64, 66) threaded in order to receive the screws 68 and 70, respectively. These screws 68 and 70 are employed to fasten the valve member 42 to the tubular handle 70. The extreme end of the valve member 42 may be provided with a threaded nipple 74 or some form of releasable fastening to receive the gas inlet hose 76.

The device as described employs cool fresh air for combustion which is drawn into the handle 72 passed the hose 76 and flows into the air passages 20 and 22, through the first mixing chamber 4 and into the 2nd mixing chamber 8 where combustion takes place. Regulation of the gas flow can take place either at the tank or by manipulation of the valve member 42. The tip 58 of the valve stem 50 is positioned to close 01f the jet passage 32 by rotation of the valve stem. This is accomplished by means of rotating the handle 72 which has fastened to it the mounting bosses 60 and 62 which are rigidly aflixed in turn to the valve stem 50.

Where it is considered sufficient to rely on the regulating valve at the gas supply, the valve 42 of the embodiment of FIGURES 1 and 2 can be eliminated. Such an arrangement is shown in FIGURE 3. The combustion chamber 78 is provided within the front tubular housing 82. This housing has afiixed within it the bushing 86, which in turn has a reduced diameter bore 88 to provide an abutment against which the interconnecting tube 84 (which provides the first mixing chamber) is fitted. The

other end of the tube 84 may be enlarged to form a housing member 80 and has a pair of air passages 94 and 96 which lead to the internal bore 92. The outer surface 90 of the housing 80 may be knurled. A threaded passage 98 has the fixed non-adjustable gas nozzle 100 threaded thereinto. This nozzle is formed with a reduced internal gas passage 102 which leads to the enlarged gas passage 104. An inlet hose 106 is attached to the threaded nipple 108 of the nozzle, and communicates with the enlarged passage 104. An appropriately shaped, e.g. hexagon, section 110 is formed on the nozzle 100 to enable the attachment of the hose.

For low gas flows with a fixed nozzle, a cross wire member 112 may be placed at the outlet of the tube 84 abutted against the reduced diameter bore 88. As shown in FIGURE 4 this cross-wire may be formed in an approximate figure 8 shape.

What have been described are preferred embodiments of the invention. It is obvious that various embodiments may be changed or combined without departing from the spirit and scope of the invention.

What I claim is:

1. A low pressure torch comprising, in combination:

a handle comprising a tubular member;

a gas inlet nozzle mounted within said tubular member;

a combustion chamber located forward of said inlet nozzle;

a conduit means leading from said handle means to said chamber; and

air passage means extending through said tubular member whereby air is caused to pass around said gas inlet nozzle and flow through said conduit means.

2. The torch of claim 1 wherein said gas inlet nozzle is positioned in the path of flow from said air passage to said conduit.

3. The torch of claim 1 wherein said gas inlet nozzle is positioned adjacent said conduit.

4. The torch of claim 2 wherein said gas inlet nozzle is positioned adjacent said conduit, and air inlet means in said conduit are provided which are so located as to pass said path of flow over said nozzle, whereby air is drawn through said handle, over said nozzle and'into said conduit.

5. The torch of claim 1 wherein said gas nozzle includes adjustable orifice means, and means afiixed to said handle means for operating upon said nozzle to adjust said orifice means.

6. The torch of claim 2 wherein said nozzle and air passage are so constructed and arranged that the gas stream is confined to a thin stream within said conduit surrounded by the air stream which flows in boundary layers along the wall of the conduit.

7. The torch of claim 1 including a cross-wire means inserted between said conduit means and combustion chamber to reduce the flame size in a predetermined manner.

References Cited UNITED STATES PATENTS 3,260,465 7/1966 Grumbein 239-430 FOREIGN PATENTS 921,434 1/1947 France.

M. HENSON WOOD, JR., Primary Examiner.

M. Y. MAR, Assistant Examiner.

US. (:1. X.R. I 126-406; 158-274; 239-4173, 427.3; 266-23 

